They are not listed twice. Just if they are listed uint64 they also work in the int configuration. This logic hasn't changed since the current master:
https://github.com/JustinTulloss/zeromq.node/blob/7dabf27bc95ec7715b0da4bc2687b5c5ea76b8c9/binding.cc#L407
https://github.com/JustinTulloss/zeromq.node/blob/7dabf27bc95ec7715b0da4bc2687b5c5ea76b8c9/binding.cc#L413
https://github.com/JustinTulloss/zeromq.node/blob/7dabf27bc95ec7715b0da4bc2687b5c5ea76b8c9/binding.cc#L421
There are no ifdefs as well.